His lawyer said it was "deeply unattractive" that Cpl Payne's senior officers faced the lesser charge of negligently performing their duties.

A court martial involving seven troops is being held at Bulford Camp, Wilts.

Two other soldiers from the Duke of Lancaster's Regiment - L/Cpl Wayne Crowcroft, 22, and Pte Darren Fallon, 23 - deny the charge of inhumane treatment.

Three more senior soldiers, including former regimental commander Colonel Jorge Mendonca, face a charge of negligently performing a duty - that of failing to ensure nine Iraqi detainees were not ill-treated.

The charges relate to the death of Baha Mousa, 26, in custody in Basra in 2003 and also the alleged ill-treatment of other detainees.

Mr Mousa, a hotel receptionist, was among a group of detainees arrested following a counter-insurgency operation.

Cpl Payne, who also denies perverting the course of justice, is the first British serviceman to be convicted of a war crime.

On Monday, Tim Owen QC, representing Cpl Payne, told the court martial's seven-man judging board: "You may think that there is something deeply unattractive, deeply unfair about a prosecution which applies one set of rules to the junior ranks - those operating at the sharp end - and a different set of rules to those higher up the chain of command."

To be guilty does not necessarily mean being the one who commits the act but could mean aiding or abetting it, he added.

He said Colonel Mendonca, Major Michael Peebles, Warrant Officer Mark Davies and three other officers not on trial had escaped the stronger charge and three individuals had been singled out.

He said Cpl Payne now accepted he used force - kicks, punches, slaps - but his lies previously in interview "were a result of the belief that he was being unfairly singled out".

Timothy Langdale QC, defence for Colonel Mendonca said his client - who was later awarded a Distinguished Service Order (DSO) for his gallant conduct in Iraq - had only been charged in "hindsight", 22 months after the alleged abuse.

Mr Langdale said the colonel, in fraught circumstances, could not have been expected to know exactly what his men were doing all the time.

Charge list

The inhumane treatment of persons charge faced by Cpl Payne, L/Cpl Wayne Crowcroft and Pte Darren Fallon, is being brought as a war crime charge under the International Criminal Court Act (ICCA) 2001.

The court martial, at the Military Court Centre at Bulford Camp on Salisbury Plain, Wiltshire, is the first time British military personnel have been prosecuted under the Act.

Sgt Kelvin Stacey, 29, of the Duke of Lancaster's Regiment, is accused of assault occasioning actual bodily harm with an alternative count of common assault.